This application is based upon and claims priority of Japanese Patent Application No. 10-246128 filed Aug. 31, 1998, and Japanese patent application No. 9-224323, filed Aug. 6, 1997, and U.S. patent application No. 09/129,367, filed Aug. 5, 1998, the contents being incorporated herein by reference.
1. Field of the Invention
The present invention relates to a microscope device, and, more particularly, the present invention relates to a microscope device which can selectively use ultraviolet light and visible light as illuminating light.
2. Description of the Related Art
In recent years, semiconductor device structures have achieved increased degrees of miniaturization. For example, in the case of a 16 M dynamic RAM, the line width has become about 0.5 xcexcm.
Microscopes having a high resolving power are necessary in order to observe semiconductor devices having such a fine structure. The use of short wavelength light sources is one way in which to increase resolving power of a microscope. Prior art microscopes have generally used tungsten lamps, halogen lamps, or the like, visible light sources. However, these known light sources do not deliver ultraviolet light. In particular, with respect to extreme ultraviolet light (DUV) having a wavelength of 300 nm or less, the amount of light necessary for observation cannot be ensured.
Mercury lamps, and the like light sources, are used for illumination when ultraviolet light is required for observation. However, the image obtained using a mercury lamp is only a monochrome image, and color information, which is one item necessary for inspection, cannot be obtained. Therefore, even with a microscope device with which observation using ultraviolet light is possible, it is also necessary to be able to perform observation using visible light. However, problems occur with a known illuminating system which illuminates with both ultraviolet light (particularly DUV light) and visible light.
A filter, dichroic mirror, or the like optical element, is used to start to selectively isolate light of some wavelength. It is known to use a visible light illuminating system and an ultraviolet light illuminating system in the same microscope, using this type of optical system.
Because DUV light in particular is harmful to the human body, the microscope device using a DUV light source must have a structure which prevents incidence of the DUV light on the eye, even if by any chance the DUV light should pass through the eyepiece lens of the microscope. However, because the known microscope device having a visible light illuminating system and an ultraviolet light illuminating system in a common observation system light path separates light using a dichroic mirror having predetermined wavelength selectivity, it is difficult to completely separate ultraviolet light and visible light. For example, when a laser or the like is used as an ultraviolet light source, there is a risk that ultraviolet light passes through the dichroic mirror and leaks into the visible light observation system.
It is an object of the present invention to overcome the problems of the prior art microscopes, and to provide a microscope which can select one of ultraviolet light and visible light as illuminating light.
It is another object of the present invention to provide a microscope device which can select one of ultraviolet light and visible light as illuminating light, and which reliably prevents ultraviolet light from being incident on the visible light observation system when visible light is selected.
Objects and advantages of the present invention are achieved in accordance with embodiments of the present invention with a microscope device comprising a visible light illuminating system to illuminate a specimen with visible light; an ultraviolet light illuminating system to illuminate the specimen with ultraviolet light; a visible light observation system to observe the specimen illuminated by the visible light illuminating system; an ultraviolet light observation system to observe the specimen illuminated by the ultraviolet light illuminating system; a first optical member to guide visible light to the specimen, which visible light is reflected from the specimen, and to guide light reflected from the specimen to the visible light observation system; a first illuminating light selection member to screen the ultraviolet light observation system from incidence of visible light; a second optical member to guide ultraviolet light to the specimen, which ultraviolet light is reflected from the specimen, and to guide light reflected from the specimen to the ultraviolet light observation system; a second illuminating light selection member to screen the visible light observation system from incidence of ultraviolet light, wherein the first optical member and the first illuminating light selection member are respectively selectively capable of arrangement in the visible light illuminating system light path, and the second optical member and the second illuminating light selection member are respectively selectively capable of arrangement in the ultraviolet light illuminating system light path.
In accordance with embodiments of the present invention, the first illuminating light selection member is arranged in the visible light illuminating system light path when the first optical member is arranged in the visible light illuminating system light path, when the second illuminating light selection member is located in the ultraviolet light illuminating system light path, and when the second optical member is arranged in the ultraviolet light illuminating system light path.
In accordance with embodiments of the present invention, when the first optical member is arranged in the visible light illuminating system light path, the second illuminating light selection member moves to the ultraviolet light illuminating system light path. Further, when the second optical member is arranged in the ultraviolet light illuminating system light path, the first illuminating light selection member moves to the visible light illuminating system light path.
In accordance with embodiments of the present invention, the second illuminating light selection member can be selected corresponding to the selected first optical member, and the first illuminating light selection member can be selected corresponding to the selected second optical member.
In accordance with embodiments of the present invention, the first optical member and the second illuminating light selection member are integrally formed, and the second optical member and the first illuminating light selection member are integrally formed.
In accordance with embodiments of the present invention, it is not necessary to respectively drive individually the first optical member and the second illuminating light selection member, and the second optical member and the first illuminating light selection member. Furthermore, the drive mechanism and guides, etc., can be small. Moreover, when electric motors are used to drive the members, the number of drive motors can be small.